The invention relates to an adjustable guide vane ring for a turbomachine, a guide vane, and an inner ring for an adjustable guide vane ring, as well as a turbomachine according to the present invention.
For establishing optimal operating conditions, turbomachines such as aircraft engines and stationary gas turbines frequently have, on the compressor side, at least one adjustable row of guide vanes having a plurality of guide vanes that can be pivoted around their vertical axis. The row of guide vanes forms with an inner ring a so-called adjustable guide vane ring. The inner ring serves for stabilizing the guide vanes and has a plurality of radial openings or recesses, each of which takes up a bearing pin on the vane side. The outer bearing of the guide vanes as well as actuation thereof is carried out via adjusting pins of the guide vanes that interact with a corresponding adjustment means. Bearing bushes, into which the bearing pins are guided, are inserted into the openings or recesses of the inner ring. It is proposed in DE102006024085 A1 to form the inner ring from two ring segments with half-circle shapes and to roll these out individually over the bearing pins of the guide vanes mounted in the housing halves. For this purpose, the ring segments are pre-tensed to a constant tensioning radius, positioned in the region of the bearing pins and then the tension is relaxed. After rolling out the half-circle ring segments, a sealing support is pushed onto these segments. A demounting of the inner ring or of the guide vane ring takes place in a similar manner. The deforming and positioning of the inner ring segments can be carried out via a tensioning device shown in DE102009004934 A1.
An inner ring for an adjustable guide vane ring, which is divided axially and thus has a front ring segment and a back ring segment, considered in the direction of flow of a primary flow, is shown in EP1319844B1. Radial recesses for receiving bearing bushes and thus the bearing pins are formed as halves in each of the ring segments, and are joined to one another in a detachable manner via nut and bolt connections.
A guide vane ring, the guide vanes of which are mounted in depressions of an inner ring via a relatively short bearing pin is shown in GB 1 049 080 A. Further prior art is known from U.S. Pat. No. 7,588,415 B2, DE 195 18 203 A1, DE 10 2009 038 A1 and from DE 28 10 240 C2.
It has been shown, however, that the use of a guide vane ring in a turbomachine having a small or reduced structural space is made difficult or is not possible at all with these known constructions.